Hydrophilic vs Hydrophobic Molecules and Water Properties

Vocabulary flashcards covering hydrophilic vs hydrophobic concepts, water polarity, hydrogen bonding, heat capacity, phase behavior, adhesion/cohesion, hydration, and hydronium formation.

Hydrophilic

Water-loving; substances that are polar or charged and readily dissolve in water.

Hydrophobic

Water-fearing; nonpolar substances that do not dissolve well in water.

Polar covalent molecule

A molecule in which electrons are shared unequally, creating partial charges; water is polar with δ+ on hydrogen and δ− on oxygen.

Partial charge (δ−) on oxygen

A symbol indicating a partial negative charge on an atom (oxygen in water), reflecting uneven electron distribution.

Hydrogen bond

A weak, transient attraction where a hydrogen atom covalently bonded to an electronegative atom (e.g., O) is attracted to another electronegative atom.

High heat capacity of water

Water can absorb a lot of heat with only a small rise in temperature due to hydrogen bonding and high specific heat.

Water expands upon freezing

Ice is less dense than liquid water; water expands when it freezes.

Cohesion

Attraction among water molecules themselves, contributing to surface tension and vertical transport in plants.

Adhesion

Attraction between water molecules and surfaces (e.g., plant xylem, straw), aiding capillary rise.

Hydration shell

The arrangement of water molecules around a dissolved ion or polar molecule; dipoles orient to stabilize the solute (e.g., NaCl).

Hydronium ion (H3O+)

Formed when water acts as a base and accepts a proton; water autoionizes to H3O+ and OH− (H2O + H2O ⇌ H3O+ + OH−).